Coating composition for optical article, spectacle lens, spectacles, and method for producing spectacle lens, and optical article and method for producing optical aritcle

ABSTRACT

A coating composition for an optical article containing a photochromic compound and two or more (meth)acrylates, the two or more (meth)acrylates containing an alicyclic difunctional (meth)acrylate and a non-cyclic tri- or higher functional (meth)acrylate.

TECHNICAL FIELD

The present invention relates to a coating composition for an opticalarticle, a spectacle lens, spectacles, and a method for producing thespectacle lens, and an optical article and a method for producing theoptical article.

BACKGROUND ART

A photochromic compound is a compound having a property (photochromicproperties) of developing color under irradiation with light in awavelength range having photoresponsiveness and fading under nonirradiation. Examples of a method for imparting photochromic propertiesto an optical article such as a spectacle lens include a method ofproviding a coating containing a photochromic compound and a curablecompound on a substrate and then curing this coating to form a curedlayer (photochromic layer) having photochromic properties (see, forexample, Patent Literature 1).

CITATION LIST Patent Literature

Patent Literature 1: WO 2003/011967

SUMMARY OF INVENTION Technical Problem

The properties desired for the optical article having photochromicproperties as described above include a high response speed to light(excellent photoresponsiveness). In addition, such an optical article isalso desired to have high color density when developing color uponreceiving light irradiation.

An aspect of the present invention provides a coating composition for anoptical article capable of forming a photochromic layer having excellentphotoresponsiveness and capable of developing color at a high density.

Solution to Problem

An aspect of the present invention relates to

a coating composition for an optical article (hereinafter, also simplyreferred to as a “composition”), containing:

a photochromic compound; and

two or more (meth)acrylates, wherein

the two or more (meth)acrylates contain

an alicyclic difunctional (meth)acrylate, and

a non-cyclic tri- or higher functional (meth)acrylate.

The coating composition for an optical article contains, as a(meth)acrylate, an alicyclic difunctional (meth)acrylate and anon-cyclic tri- or higher functional (meth)acrylate. Thus, in thephotochromic layer formed by curing this composition, the photochromiccompound can exhibit excellent photoresponsiveness, and can developcolor at a high density upon receiving light irradiation.

Advantageous Effects of Invention

According to an aspect of the present invention, it is possible toprovide a coating composition for an optical article capable of forminga photochromic layer having excellent photoresponsiveness and capable ofdeveloping color at a high density upon receiving light irradiation.According to another aspect of the present invention, it is possible toprovide a spectacle lens having a photochromic layer, the spectacle lenshaving excellent photoresponsiveness and capable of developing color ata high density upon receiving light irradiation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows evaluation results of color density in Examples andComparative Examples.

FIG. 2 shows evaluation results of photoresponsiveness (fading rate) inExamples 1 to 3 and Comparative Example 1.

FIG. 3 shows evaluation results of curability in Examples andComparative Examples.

DESCRIPTION OF EMBODIMENTS [Coating Composition for Optical Article]

A coating composition for an optical article according to an aspect ofthe present invention contains a photochromic compound and two or more(meth)acrylates. These components will be further described in detailbelow.

<(Meth)acrylate>

In the present invention and the present specification, the term“(meth)acrylate” is used in the meaning of encompassing acrylate andmethacrylate. The “acrylate” is a compound having one or more acryloylgroups in one molecule. The “methacrylate” is a compound having one ormore methacryloyl groups in one molecule. In the present invention andthe present specification, the term “methacrylate” refers to thosecontaining only a methacryloyl group as a (meth)acryloyl group, andthose containing both an acryloyl group and a methacryloyl group as a(meth)acryloyl group are referred to as an “acrylate”. The acryloylgroup may be contained in the form of an acryloyloxy group, and themethacryloyl group may be contained in the form of a methacryloyloxygroup. The term “(meth)acryloyl group” described below is used to meanto encompass an acryloyl group and a methacryloyl group. The term“(meth) acryloyloxy group” is used to mean to encompass an acryloyloxygroup and a methacryloyloxy group. In addition, unless otherwisespecified, the group described may have a substituent or may beunsubstituted. When a group has a substituent, examples of thesubstituent include an alkyl group (for example, an alkyl group having 1to 6 carbon atoms), a hydroxyl group, an alkoxy group (for example, analkoxy group having 1 to 6 carbon atoms), a halogen atom (for example, afluorine atom, a chlorine atom, or a bromine atom), a cyano group, anamino group, a nitro group, an acyl group, and a carboxyl group. Inaddition, the expression “number of carbon atoms” in the group having asubstituent means the number of carbon atoms of a portion not containinga substituent.

The composition contains two or more (meth)acrylates. One of them is analicyclic difunctional (meth)acrylate, and the other is a non-cyclictri- or higher functional (meth)acrylate. The alicyclic difunctional(meth)acrylate refers to a compound having an alicyclic structure andhaving two (meth)acryloyl groups contained in one molecule. In thepresent invention and the present specification, the term “non-cyclic”means not containing a cyclic structure. On the other hand, the term“cyclic” means containing a cyclic structure. The non-cyclic tri- orhigher functional (meth)acrylate refers to a compound not containing acyclic structure and having three or more (meth)acryloyl groupscontained in one molecule. Inclusion of these compounds is presumed tobe the reason why the photochromic layer formed from this compositioncan develop color at a high density upon receiving light irradiation andcan exhibit excellent photoresponsiveness.

(Alicyclic Difunctional (Meth)acrylate)

The alicyclic difunctional (meth)acrylate can be, for example, acompound having a structure represented by R¹-(L¹)n1-Q-(L²)n2-R². Here,Q represents a divalent alicyclic group, R¹ and R² each independentlyrepresent a (meth)acryloyl group or a (meth)acryloyloxy group, L¹ and L²each independently represent a linking group, and n1 and n2 eachindependently represent 0 or 1. The divalent alicyclic group representedby Q is preferably an alicyclic hydrocarbon group having 3 to 20 carbonatoms. Examples thereof include a cyclopentylene group, a cyclohexylenegroup, a cycloheptylene group, a cyclooctylene group, atricyclodecanylene group, and an adamantylene group. Examples of thelinking group represented by L¹ and L² include an alkylene group. Thealkylene group can be, for example, an alkylene group having 1 to 6carbon atoms.

Specific examples of the alicyclic difunctional (meth)acrylate includecyclohexanedimethanol di(meth)acrylate, ethoxylatedcyclohexanedimethanol di(meth)acrylate, propoxylatedcyclohexanedimethanol di(meth)acrylate, ethoxylated propoxylatedcyclohexanedimethanol di(meth)acrylate, tricyclodecanedimethanoldi(meth)acrylate, ethoxylated tricyclodecanedimethanol di(meth)acrylate,propoxylated tricyclodecanedimethanol di(meth)acrylate, and ethoxylatedpropoxylated tricyclodecanedimethanol di(meth)acrylate. The molecularweight of the alicyclic difunctional (meth)acrylate can be, for example,in the range of 200 to 400, but is not limited to this range. In thepresent invention and the present specification, as the molecular weightof the polymer, a theoretical molecular weight calculated from astructural formula determined by structural analysis of the compound ora raw material charging ratio in the production is employed. Thealicyclic difunctional (meth)acrylate may contain, as a (meth)acryloylgroup, only an acryloyl group, only a methacryloyl group, or an acryloylgroup and a methacryloyl group. In an aspect, the alicyclic difunctional(meth)acrylate preferably contains only a methacryloyl group as a(meth)acryloyl group, that is, the alicyclic difunctional (meth)acrylateis preferably methacrylate.

(Non-Cyclic Tri- or Higher Functional (Meth)acrylate)

The non-cyclic tri- or higher functional (meth)acrylate is preferably atrifunctional to pentafunctional (meth)acrylate, more preferably atrifunctional or tetrafunctional (meth)acrylate, and still morepreferably a trifunctional (meth)acrylate. Specific examples of thenon-cyclic tri- or higher functional (meth)acrylate includepentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,dipentaerythritol tetra(meth)acrylate, trimethylolethanetri(meth)acrylate, trimethylolpropane tri(meth)acrylate,ditrimethylolpropane tetra(meth)acrylate, tetramethylolmethanetetra(meth)acrylate, and tetramethylolmethane tri(meth)acrylate. Themolecular weight of the non-cyclic tri- or higher functional(meth)acrylate can be, for example, in the range of 200 to 400, but isnot limited to this range. The non-cyclic tri- or higher functional(meth)acrylate may contain, as a (meth)acryloyl group, only an acryloylgroup, only a methacryloyl group, or an acryloyl group and amethacryloyl group. In an aspect, the non-cyclic tri- or higherfunctional (meth)acrylate preferably contains only a methacryloyl groupas a (meth)acryloyl group, that is, the non-cyclic tri- or higherfunctional (meth)acrylate is preferably methacrylate.

(Another (Meth)acrylate)

The composition can contain, as a (meth)acrylate, one or two or morealicyclic difunctional (meth)acrylates, and can contain one or two ormore non-cyclic tri- or higher functional (meth)acrylates. Thecomposition may or may not contain one or more other (meth)acrylates inaddition to these (meth)acrylates. The other (meth)acrylate can be used,for example, for adjusting the viscosity of the composition. The other(meth)acrylate can be, for example, a non-cyclic or cyclic di- or higherfunctional (meth)acrylate. The other (meth)acrylate can be adifunctional to pentafunctional (meth)acrylate, preferably adifunctional to tetrafunctional (meth)acrylate, more preferably adifunctional or trifunctional (meth)acrylate, and still more preferablya difunctional (meth)acrylate. The molecular weight of the other(meth)acrylate can be, for example, in the range of 150 to 350, but isnot limited to this range.

In an aspect, the other (meth)acrylate can be a non-cyclic difunctional(meth)acrylate. Specific examples thereof include neopentyl glycoldi(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate,propoxylated neopentyl glycol di(meth)acrylate, 1,6-hexanedioldi(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanedioldiacrylate, ethylene glycol di(meth)acrylate, diethylene glycoldi(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, andpolypropylene glycol di(meth)acrylate.

The content of the alicyclic difunctional (meth)acrylate is preferably50 mass % or more, more preferably 55 mass % or more, and still morepreferably 60 mass % or more when the total amount of the two or more(meth)acrylates contained in the composition is 100 mass %. The contentof the alicyclic difunctional (meth)acrylate can be, for example, 80mass % or less, and can be more than 80 mass %. Meanwhile, the contentof the non-cyclic tri- or higher functional (meth)acrylate is preferably5 mass % or more, more preferably 7 mass % or more, and still morepreferably 10 mass % or more when the total amount of the two or more(meth)acrylates contained in the composition is 100 mass %. The contentof the non-cyclic tri- or higher functional (meth)acrylate is preferably20 mass % or less, and more preferably 15 mass % or less. The totalcontent of the alicyclic difunctional (meth)acrylate and the non-cyclictri- or higher functional (meth)acrylate is preferably 55 mass % ormore, more preferably 60 mass % or more, still more preferably 65 mass %or more, and still even more preferably 70 mass % or more when the totalamount of the two or more (meth)acrylates contained in the compositionis 100 mass %. In addition, the total content of the alicyclicdifunctional (meth)acrylate and the non-cyclic tri- or higher functional(meth)acrylate can be, for example, 90 mass % or less, and also 85 mass% or less. Meanwhile, the content of the other (meth)acrylate other thanthe alicyclic difunctional (meth)acrylate and the non-cyclic tri- orhigher functional (meth)acrylate can be 0 mass % or may be more than 0mass % when the total amount of the two or more (meth)acrylatescontained in the composition is 100 mass %. When the other(meth)acrylate is contained in the composition, the content thereof ispreferably 3 mass % or more, more preferably 5 mass % or more, stillmore preferably 7 mass % or more, and more preferably 10 mass % or more,when the total amount of the two or more (meth)acrylates contained inthe composition is 100 mass %. The content of the other (meth)acrylateis preferably 40 mass % or less, more preferably 35 mass % or less, andstill more preferably 30 mass % or less. In addition, the compositioncan contain the (meth)acrylate at a content of, for example, 80 to 99.9mass % relative to 100 mass % of the total amount of the composition.

<Photochromic Compound>

The composition contains a photochromic compound together with the twoor more (meth)acrylates. As the photochromic compound contained in thecomposition, a known compound exhibiting photochromic properties can beused. The photochromic compound can exhibit photochromic propertiesagainst, for example, ultraviolet rays. Examples of the photochromiccompound include compounds having a known skeleton exhibitingphotochromic properties, such as a fulgimide compound, a spirooxazinecompound, a chromene compound, and an indeno-fused naphthopyrancompound. The photochromic compound can be used singly or in combinationof two or more thereof. The content of the photochromic compound of thecomposition can be, for example, approximately 0.1 to 15 mass % relativeto 100 mass % of the total amount of the composition, but is not limitedto this range.

<Optional Component>

Since the (meth)acrylate described above is a curable compound, thecomposition containing the (meth)acrylate can be a curable composition,and can be cured to form a cured layer when subjected to a curingtreatment. The composition can contain a polymerization initiator forinitiating a curing reaction (also referred to as a polymerizationreaction). As the polymerization initiator, a known polymerizationinitiator such as a photopolymerization initiator or a thermalpolymerization initiator can be used according to the type of the curingreaction. The amount of the polymerization initiator used may bedetermined according to the polymerization condition, the type of thepolymerization initiator, and the type of the curable compound containedin the curable composition.

To the composition, known additives that can be added to the compositioncontaining the photochromic compound, for example, additives such as asurfactant, an antioxidant, a radical scavenger, a photostabilizer, anultraviolet absorber, a coloring inhibitor, an antistatic agent, afluorescent dye, a dye, a pigment, a fragrance, a plasticizer, and asilane coupling agent can be further added in any amounts. As theseadditives, known compounds can be used.

The composition can be prepared by mixing the various componentsdescribed above simultaneously or sequentially in any order.

The composition is a coating composition for an optical article. Thecoating composition for an optical article means a composition appliedto a substrate or the like for producing an optical article. Examples ofthe optical article include various lenses, and preferably include aspectacle lens. A spectacle lens produced by applying the composition toa lens substrate has a photochromic layer, and can exhibit photochromicproperties.

[Spectacle Lens and Method for Producing Spectacle Lens]

An aspect of the present invention relates to

a spectacle lens including:

a lens substrate; and

a photochromic layer formed by curing the composition, and

a method for producing a spectacle lens, including:

applying the composition onto the lens substrate; and

subjecting the applied composition to a curing treatment to form aphotochromic layer. Hereinafter, the spectacle lens and the method forproducing a spectacle lens will be described in more detail.

<Lens Substrate>

The lens substrate included in the spectacle lens can be a plastic lenssubstrate or a glass lens substrate. The glass lens substrate can be,for example, a lens substrate made of inorganic glass. As the lenssubstrate, a plastic lens substrate is preferable from the viewpoint ofbeing light, hardly broken, and easy to handle. Examples of the plasticlens substrate include a styrene resin including a (meth)acrylic resin,a polycarbonate resin, an allyl resin, an allyl carbonate resin such asdiethyleneglycol bis(allylcarbonate) resin (CR-39), a vinyl resin, apolyester resin, a polyether resin, a urethane resin obtained throughreaction between an isocyanate compound and a hydroxy compound such asdiethylene glycol, a thiourethane resin obtained through reactionbetween an isocyanate compound and a polythiol compound, and a curedproduct (generally referred to as a transparent resin) obtained bycuring a curable composition containing a (thio)epoxy compound havingone or more intermolecular disulfide bonds. The lens substrate may beundyed (a colorless lens) or dyed (a dyed lens). The refractive index ofthe lens substrate can be, for example, approximately 1.60 to 1.75.Provided that the refractive index of the lens substrate is not limitedto the above range, but may be within the above range or deviatetherefrom. In the present invention and the present specification, therefractive index refers to a refractive index with respect to lighthaving a wavelength of 500 nm. In addition, the lens substrate may be alens having power (so-called prescription lens) or a lens having nopower (so-called plain glass lens).

The spectacle lens can be various lenses such as a single-vision lens, amultifocal lens, and a progressive addition lens. The type of the lensis determined depending on the shapes of both surfaces of the lenssubstrate. Furthermore, the surface of the lens substrate may be aconvex surface, a concave surface, or a flat surface. In a common lenssubstrate and spectacle lens, the object-side surface is a convexsurface, and the eyeball-side surface is a concave surface. However, thepresent invention is not limited thereto. The photochromic layer can beusually provided on the object-side surface of the lens substrate, butmay be provided on the eyeball-side surface.

The photochromic layer formed using the composition may be directlyprovided on the surface of the lens substrate, or may be indirectlyprovided with one or more other layers interposed between thephotochromic layer and the lens substrate. Examples of the other layerinclude a primer layer for improving adhesion between the photochromiclayer and the lens substrate. Such a primer layer is known.

<Photochromic Layer>

The photochromic layer of the spectacle lens can be formed by applyingthe composition onto the surface of the lens substrate directly orindirectly with one or more other layers interposed between thephotochromic layer and the lens substrate, and subjecting the appliedcomposition to a curing treatment. As a coating method, a known coatingmethod such as a spin coating method or a dip coating method can beemployed. The spin coating method is preferable from the viewpoint ofuniformity of coating. The curing treatment can be light irradiationand/or heat treatment. Light irradiation is preferable from theviewpoint of allowing the curing reaction to proceed in a short time.The curing treatment condition may be determined according to the typesof various components ((meth)acrylate, polymerization initiator, and thelike described above) contained in the composition and the constitutionof the composition. The thickness of the photochromic layer thus formedis, for example, preferably in the range of 5 to 80 μm, and morepreferably in the range of 20 to 60 μm.

The spectacle lens having the photochromic layer may or may not have oneor more functional layers in addition to the photochromic layer.Examples of the functional layer include layers known as functionallayers of a spectacle lens, such as a hard coat layer, an antireflectivelayer, a water-repellent or hydrophilic antifouling layer, and anantifogging layer.

[Spectacles]

An aspect of the present invention relates to spectacles including thespectacle lens. Details of the spectacle lens included in the spectaclesare as described above. A spectacle lens including such a spectacle lenscan exhibit an anti-glare effect like sunglasses, provided by thephotochromic compound contained in the photochromic layer developingcolor upon receiving sunlight irradiation in outdoors, for example, andcan also recover transparency due to discoloration of the photochromiccompound when returning to indoors. A known technique can be applied tothe configuration of a frame or the like of the above spectacles.

[Optical Article and Method for Producing Optical Article]

An aspect of the present invention relates to

an optical component including:

a substrate; and

a photochromic layer formed by curing the composition, and

a method for producing an optical article, including:

applying the composition onto the substrate; and

subjecting the applied composition to a curing treatment to form aphotochromic layer.

An aspect of the optical article is the spectacle lens described above.In addition, examples of an aspect of the optical article include agoggle lens, a visor (eaves) portion of a sun visor, a shield member ofa helmet, and the like. An optical article having an anti-glare functioncan be obtained by applying the above composition onto the substrate forthese optical articles and subjecting the applied composition to acuring treatment to form a photochromic layer.

EXAMPLES

Hereinafter, the present invention will be further described based onexamples. However, the present invention is not limited to aspectsillustrated in the examples.

Example 1 <Preparation of Coating Composition for Optical Article>

In a plastic container, 68 mass % (relative to 100 mass % of the totalof (meth)acrylates) of tricyclodecane dimethanol dimethacrylate(alicyclic difunctional (meth)acrylate), 12 mass % of trimethylolpropanetrimethacrylate (non-cyclic trifunctional (meth)acrylate), and 20 mass %of neopentyl glycol dimethacrylate (another (meth)acrylate) were mixedto prepare a (meth)acrylate mixture. To this (meth)acrylate mixture, aphotochromic compound (indeno-fused naphthopyran compound represented bythe structural formula described in U.S. Pat. No. 5,645,767 B), aphotopolymerization initiator (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide), an antioxidant(bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate][ethylenebis(oxyethylene)]), and a photostabilizer(bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate) were mixed andsufficiently stirred, and then a silane coupling agent(γ-methacryloxypropyltrimethoxysilane) was added dropwise with stirring.Thereafter, the resultant was defoamed by an automatic planetarystirring defoaming device.

A coating composition for an optical article having the compositionshown in Table 1 below was prepared by the above method.

TABLE 1 Component Content (mass %) Alicyclic difunctional 58.97(meth)acrylate Non-cyclic trifunctional 10.41 (meth)acrylate Another(meth)acrylate 17.35 Photochromic compound 2.60 Photopolymerizationinitiator 0.26 Antioxidant 2.60 Photostabilizer 2.60 Silane couplingagent 5.20

<Production of Spectacle Lens>

A plastic lens substrate (product name EYAS, manufactured by HOYACorporation; center wall thickness: 2.5 mm, radius: 75 mm, S: −4.00) wasimmersed in a 10 mass % aqueous sodium hydroxide solution (liquidtemperature: 60° C.) for 5 minutes, then washed with pure water, anddried. Thereafter, a primer layer was formed on the convex surface(object-side surface) of the plastic lens substrate. Specifically, anaqueous polyurethane resin liquid (polycarbonate polyol-basedpolyurethane emulsion; viscosity: 100 CPS, solid content concentration:38 mass %) was applied to the convex surface of the plastic lenssubstrate by a spin coating method in an environment of a temperature of25° C. and a relative humidity of 50%, and then naturally dried for 15minutes to form a primer layer having a thickness of 5.5 μm.

The composition prepared above was applied onto the primer layer by aspin coating method. The spin coating was performed by the methoddescribed in JP 2005-218994 A. Thereafter, the composition applied ontothe plastic lens substrate was irradiated with ultraviolet rays(wavelength: 405 nm) in a nitrogen atmosphere (oxygen concentration: 500ppm or less) to cure the composition, thereby forming a photochromiclayer. The thickness of the formed photochromic layer was 45 μm.

For each of Examples and Comparative Examples, a plurality of spectaclelenses in which the degree of progress of the curing reaction of thephotochromic layer was changed by changing the light irradiation timewere produced.

Example 2

A spectacle lens having a photochromic layer was produced in the samemanner as in Example 1 except that the alicyclic difunctional(meth)acrylate was changed to tricyclodecane dimethanol diacrylate.

Example 3

A spectacle lens having a photochromic layer was produced in the samemanner as in Example 1 except that neopentyl glycol dimethacrylate wasnot used.

Comparative Example 1

A spectacle lens having a photochromic layer was produced in the samemanner as in Example 1 except that ethoxylated bisphenol Adimethacrylate (2,2 bis[4-(methacryloxypolyethoxy)phenyl]propane (EO 10mol)) was used instead of the alicyclic difunctional (meth)acrylate.

Comparative Example 2

A spectacle lens having a photochromic layer was produced in the samemanner as in Example 1 except that polyethylene glycol diacrylate(molecular weight: 508) was used instead of the alicyclic difunctional(meth)acrylate.

[Evaluation Method] <Color Density>

The color density was evaluated by the following method according to JIST7333:2005.

The surface of photochromic layer of each of the spectacle lenses ofExamples and Comparative Examples was irradiated with light using axenon lamp through an air mass filter for 15 minutes (900 seconds) tocause a photochromic compound in the photochromic layer to developcolor. The transmittance (measurement wavelength: 550 nm) at the time ofcolor development was measured by a spectrophotometer manufactured byOtsuka Electronics Co., Ltd. The light irradiation was performed so thatthe irradiance and tolerance of the irradiance were values shown in thefollowing Table 2 as specified in JIS T7333:2005.

TABLE 2 Wavelength range Irradiance Tolerance of (nm) (W/m²) irradiance(W/m²) 300 to 340 <2.5 — 340 to 380 5.6 ±1.5 380 to 420 12 ±3.0 420 to460 12 ±3.0 460 to 500 26 ±2.6

A smaller value of the transmittance measured above means that thephotochromic compound develops color at a high density.

FIG. 1 shows a graph in which the transmittance obtained as describedabove is plotted with respect to the light irradiation time at the timeof forming the photochromic layer as the evaluation results of colordensity.

<Photoresponsiveness (Fading Rate)>

The photoresponsiveness (fading rate) was evaluated by the followingmethod.

The transmittance (measurement wavelength: 550 nm) of each of thespectacle lenses of Examples and Comparative Examples before lightirradiation (undeveloped state) was measured by a spectrophotometermanufactured by Otsuka Electronics Co., Ltd. The transmittance measuredhere is referred to as “initial transmittance”.

The surface of the photochromic layer of each of the spectacle lenses ofExamples and Comparative Examples was irradiated with light using axenon lamp through an air mass filter for 15 minutes (900 seconds) tocause a photochromic compound in the photochromic layer to developcolor. The transmittance at color development was measured in the samemanner as described above.

Thereafter, the time (half-life) required from the time when the lightirradiation was stopped until the transmittance reached [(initialtransmittance−transmittance at color development)/2] was measured. Asmaller value of the half-life measured in this way is determined toexhibit high fading rate and excellent photoresponsiveness.

The hardness (Martens hardness) of the photochromic layer of thespectacle lens after the evaluation was measured by the followingmethod. The degree of progress of the curing reaction of thephotochromic layer can be determined by the hardness of the photochromiclayer, and a harder photochromic layer is determined as better progressof the curing reaction.

Using an ultra-micro indentation hardness tester ENT-2100, manufacturedby ELIONIX INC., an indenter was pressed against the surface of thephotochromic layer with a load of 100 mgf, and the surface area wherethe indenter penetrated at this time was measured from the indentationdepth. The Martens hardness (kgf/mm²) was determined as “load/surfacearea where the indenter penetrated”.

FIG. 2 shows a graph in which the half-life is plotted with respect tothe Martens hardness obtained as described above as the evaluationresults of photoresponsiveness (fading rate) for each of thephotochromic layers of Examples 1 to 3 and Comparative Example 1.

The results shown in FIG. 1 demonstrate that the spectacle lenses ofExamples 1 to 3 and Comparative Example 1 are superior to the spectaclelens of Comparative Example 2 in terms of color density.

On the other hand, comparing Examples 1 to 3 with Comparative Example 1in terms of photoresponsiveness (fading rate), the spectacle lenses ofExamples 1 to 3 have a smaller half-life value at the same hardness thanthat of Comparative Example 1, and thus is excellent inphotoresponsiveness, as shown in FIG. 2.

The above results show that the spectacle lenses of Examples 1 to 3 havehigh color density of the photochromic compound contained in thephotochromic layer, and is excellent in photoresponsiveness.

FIG. 3 is a graph in which the Martens hardness measured as describedabove is plotted with respect to the light irradiation time at the timeof forming the photochromic layer as the evaluation results ofcurability for each of the spectacle lenses of Examples and ComparativeExamples. The results shown in FIG. 3 demonstrate that the spectaclelenses of Examples 1 to 3 exhibited higher Martens hardness of thephotochromic layer at the same light irradiation time than that of thespectacle lenses of Comparative Examples 1 and 2. This result shows thatcombined use of an alicyclic difunctional (meth)acrylate and anon-cyclic tri- or higher functional (meth)acrylate as the(meth)acrylate is preferable in view of forming a photochromic layerhaving high hardness.

Finally, the above described aspects will be summarized.

According to an aspect, there is provided a coating composition for anoptical article containing a photochromic compound and two or more(meth)acrylates, the two or more (meth)acrylates containing an alicyclicdifunctional (meth)acrylate and a non-cyclic tri- or higher functional(meth)acrylate.

According to the coating composition for an optical article, aphotochromic layer having excellent photoresponsiveness and capable ofdeveloping color at a high density can be formed.

In an aspect, the two or more (meth)acrylates can further contain anon-cyclic difunctional (meth)acrylate.

In an aspect, the composition can contain the alicyclic difunctional(meth)acrylate in an amount of 50 mass % or more relative to the totalamount of the two or more (meth)acrylates.

In an aspect, the alicyclic difunctional (meth)acrylate can bemethacrylate.

According to an aspect, there is provided a spectacle lens including alens substrate and a photochromic layer formed by curing thecomposition.

The spectacle lens can have a photochromic layer having excellentphotoresponsiveness and capable of developing color at a high density.

According to an aspect, spectacles including the spectacle lens areprovided.

According to an aspect, there is provided an optical article including asubstrate and a photochromic layer formed by curing the composition.

According to an aspect, there is provided a method for producing anoptical article, including applying the composition onto a substrate andsubjecting the applied composition to a curing treatment to form aphotochromic layer.

According to the above production method, an optical article having ananti-glare function can be provided.

In an aspect, the optical article can be a spectacle lens, a gogglelens, a visor portion of a sun visor, a shield member of a helmet, andthe like.

The various aspects described in this specification can be combined intwo or more in any combination.

The embodiment disclosed herein is an example in every respect andshould not be restrictively understood. The scope of the presentinvention is defined not by the above description but by claims, andintends to include all modifications within meaning and a scope equal toclaims.

INDUSTRIAL APPLICABILITY

The present invention is useful in the technical field of spectacles,goggles, sun visors, helmets, and the like.

1. A coating composition for an optical article, comprising: aphotochromic compound; and two or more (meth)acrylates, wherein the twoor more (meth)acrylates contain an alicyclic difunctional(meth)acrylate, and a non-cyclic tri- or higher functional(meth)acrylate.
 2. The coating composition for an optical articleaccording to claim 1, wherein the two or more (meth)acrylates furthercontain a non-cyclic difunctional (meth)acrylate.
 3. The coatingcomposition for an optical article according to claim 1, wherein thecoating composition contains the alicyclic difunctional (meth)acrylatein an amount of 50 mass % or more relative to a total amount of the twoor more (meth)acrylates.
 4. The coating composition for an opticalarticle according to claim 1, wherein the alicyclic difunctional(meth)acrylate is methacrylate.
 5. A spectacle lens comprising: a lenssubstrate; and a photochromic layer formed by curing the coatingcomposition for an optical article according to claim
 1. 6. Spectaclescomprising the spectacle lens according to claim
 5. 7. An opticalarticle comprising: a substrate; and a photochromic layer formed bycuring the coating composition for an optical article according toclaim
 1. 8. The optical article according to claim 7, wherein theoptical article is a goggle lens.
 9. The optical article according toclaim 7, wherein the optical article is a visor portion of a sun visor.10. The optical article according to claim 7, wherein the opticalarticle is a shield member of a helmet.
 11. A method for producing anoptical article, comprising: applying the coating composition for anoptical article according to claim 1 onto a substrate; and subjectingthe applied coating composition for an optical article to a curingtreatment to form a photochromic layer.
 12. The method for producing anoptical article according to claim 11, wherein the optical article is aspectacle lens.
 13. The method for producing an optical articleaccording to claim 11, wherein the optical article is a goggle lens. 14.The method for producing an optical article according to claim 11,wherein the optical article is a visor portion of a sun visor.
 15. Themethod for producing an optical article according to claim 11, whereinthe optical article is a shield member of a helmet.